A front lamp to brighten up a road ahead of a vehicle at night is equipped on a front of a vehicle. On a rear side of the vehicle, a back lamp which is turned on when shifting into a reverse gear, a brake lamp which is turned on when a brake pedal is pressed, a rear fog lamp which is turned on by environmental factors such as fog, drizzle, and a blizzard, and an indicator lamp which is turned on when changing lane, are equipped.
In general, when the front lamp does not operate normally, since the driver may possibly check it while driving, an accident due to a breakdown of the front lamp is rare.
However, in case of the rear lamp, since it is mostly switched on and off by a driving behavior of the driver, it is difficult for the driver to determine the operation status of the rear lamp as clearly in real time as a breakdown of the front lamp.